1. Field of the Invention
The present invention generally relates to space vehicles, and more particularly to asymmetrical space vehicle systems having an aerospike attached to the nose of an external tank in order to alter the aerodynamic effect on the entire vehicle during space flight and on-orbit benefits. The present invention is particularly adapted for use with aerodynamically asymmetric vehicles such as the space shuttle, and shuttle derived vehicles, although its principle of operation can also be applied to symmetric vehicles.
2. Discussion of Prior Art
Numerous attempts have been made in a variety of vehicles to alter the aerodynamic flow around the vehicles by suing an elongated or spiked element on the nose thereof.
NICHOLSON et al., U.S. Pat. No. 3,416,758, discloses a self-balancing spike control which is adapted to provide a system for orienting a spike or rod at the nose of an aircraft so that the fluid shock cone will be positioned to completely protect the nose or leading edge of a supersonic vehicle. The apparatus is adapted to be positioned on a supersonic vehicle nose tube which is misaligned with an airstream. A spike is positioned on the front of the nose and can be angled to form a protective cone which completely encloses the region to be protected. The spike forms a uniform region which prevents turbulent hot-spots from occurring at or near the surface of a window. By positioning the spike or rod upstream of the window or sensor, the airstream is diverted to protect the window from undue heating and erosion.
PATAPIS, U.S. Pat. No. 3,643,901, discloses a ducted spike diffuser for reducing drag and erosion of blunt bodies which operate at supersonic speeds. A diffuser is attached to a randome and is mounted on a spike shank. A bow tip shock results at a detached position forwardly of the diffuser and continues outwardly therefrom.
SCHOPPE, U.S. Pat. No. 3,620,484, discloses a method and apparatus of reducing shock waves created by solid bodies moving at supersonic speeds. The apparatus for reducing the shock wave, drag and sonic boom uses a thermodynamic cycle. By using a small-diameter gas tube or pipe which protrudes from the front of the body, the nose of the small body will generate relatively low shock waves. If no combustion occurs, the head end of the main body will generate an additional strong shock wave in conventional fashion. This will serve to maintain air located around the nose of the supersonic body and may also serve to eliminate the sonic boom which accompanies shock waves.
GRAHAM, U.S. Pat. No. 4,114,836, discloses an aircraft which has a nose configured to reduce drag and sonic boom. The aircraft has a fuselage, wings, a horizontal elevator, and a rudder. A plurality of passageways extend through each wing section and diverge from the front towards the rear of the vehicle. The longitudinal axes of the passageways are aligned with the flight path, insofar as possible.
TAKACS, U.S. Pat. No. 2,980,370, discloses a supersonic flying body which includes a nose having the outline of a cone. A stepped portion is provided behind the nose together with a cylindrical neck for connecting the nose to the trunk or body of the flying craft. The nose is comprised of a material which is sufficiently resistant to heat and vibration in order to withstand the stresses which exist at supersonic speeds. If the flying body moves at a speed greater than the speed of sound, compressed waves will be produced at the nose in a gas, e.g., air, which surrounds the flying body. These waves will diverge in the direction of a generating surface of the nose. The flying body will thus be surrounded by an envelope of highly compressed gas which will protect the flying body from external influences, such as missiles, which will be warded off of their courses by the action of the potential current that is generated about the flying body.
Additionally, an aerospike has been used in conjunction with Trident II submarine launched ballistic missiles. This aerospike comprises a telescopic boom section which is extended, upon generation of a gas, from the curved nose fairing of a symmetrical Trident missile. The end of the boom section in each of these missiles comprises a flat, generally discoidal shaped object.
None of the prior art which is listed above discloses an aerospike which can be attached to an aerodynamically asymmetrical vehicle nor which can vary in length as a function of changing aerodynamic regimen in order to enhance aerodynamic flow, reduce drag, and increase vehicle drag. Further, none of the prior art discloses the use of an elongated spike having a rounded disc-like tip at an outer end thereof and which has an optimized length.